1. Field of the Invention
The present invention relates generally to system management buses used to control modules in a networking chassis. More particularly, the present invention relates to a fault tolerant system management bus architecture for transmitting communications and control information between networking modules in a networking chassis.
2. Discussion of the Related Art
In a conventional networking chassis, for communication and control of individual networking modules, a single network connected to all of the networking modules is provided. This is called an "out-of-band" network. The out-of-band network typically is not accessible from outside the networking chassis and is only used to transmit communication and control information ("system management information") between networking modules within the chassis. The network that connects the ports on the networking chassis together for purposes of transmitting data from one workstation or network segment to another is called the "in-band" network. In a conventional networking chassis, the central processing unit (CPU) located on the network module that controls communication over the in-band network is also used to control data transmission over the out-of-band network as well. One problem with this type of system is that no fault tolerance is provided. If a problem occurs with the out-of-band network or with the networking module itself, there is no other path provided for transmission of system management information.
Some conventional networking chassis have provided two out-of-band networks wherein if there is a failure in one of the networks, system management information can be transmitted over the second out-of-band network. However, even in these systems, if the CPU of the networking module is off or has failed, no information regarding the status of the networking module can be obtained.
Therefore, an object of the present invention is to provide a system management bus architecture for a networking chassis that provides fault tolerant operation if there is a failure of the primary out-of-band network on a networking module.
Another object of the present invention is to provide a system management bus architecture for a networking chassis that allows information to be gathered about a module even if there is a failure of the primary out-of-band network.
Another object of the present invention is to provide a system management bus architecture for a networking chassis that allows for information to be gathered about the physical conditions and environment of the networking module.